prescribed with other mechanisms of action intended but also having anticholinergic effects, and

not typically thought of as having anticholinergic effects.

A high anticholinergic burden in older people is associated with an increased risk of cognitive decline.

Be alert to anticholinergic adverse effects in your older patient.

Consider reducing the anticholinergic burden where possible.

Thinking clearly about the anticholinergic burden

Older people can be particularly sensitive to the anticholinergic effects of medicines.1 Adverse effects may arise from an individual anticholinergic medicine, and from the cumulative effects of multiple medicines with varying degrees of anticholinergic properties.2-4

The anticholinergic burden may be unintentionally increased by medicines prescribed with other mechanisms of action intended, but also having anticholinergic effects, such as antihistamines, tricyclic antidepressants and antipsychotics.2 In addition, medicines not typically thought of as having anticholinergic effects, such as citalopram, mirtazapine and metoclopramide, when added to other strongly anticholinergic medicines, may tip the balance of the cumulative anticholinergic burden and result in significant adverse effects.2, 4, 5

Older Australians commonly use medicines with anticholinergic effects; at any point in time 21-33% of Australians aged over 60 years use at least one medicine with anticholinergic effects.6-8 A cumulative anticholinergic burden in older people with co-morbidities who are taking multiple medicines is associated with an increased risk of confusion, cognitive and physical decline, delirium, hospitalisation and death.2, 3, 9-11

This therapeutic brief provides information on anticholinergic adverse effects and outlines steps to take to reduce the anticholinergic burden.

Ask yourself and your patient: What are the adverse effects and potential outcomes?

Anticholinergic adverse effects may be subtle or severe (see Figure 1). In older people, the effects may be overlooked and considered part of the natural ageing process or attributed to the progression of underlying disease.1, 5 Consequences of blurred vision, dizziness or memory loss from an anticholinergic burden may include loss of independence, falls or motor vehicle accidents.1, 12 Acute confusion or delirium may result in hospitalisation, functional and cognitive decline or aged care facility placement.13, 14

Be alert to possible anticholinergic adverse effects in your older patient, as the anticholinergic load differs between medicines, and individuals differ in their ability to tolerate them.4

Consider that any worsening of chronic conditions, new symptoms or adverse events may be the result of medicines with anticholinergic effects, especially if they occur after changes in the medicine regimen.4, 13

Avoid treating adverse effects with medicines.1

Ask: What is the burden?

While exact quantification of a medicine’s anticholinergic effect is difficult,16 it is estimated one medicine with strong anticholinergic effects is likely to cause two or more anticholinergic adverse effects in more than 70% of older patients.17 Additionally, older patients prescribed two or more anticholinergic medicines are at a significantly increased risk of hospitalisation for confusion or dementia.10 Table 1 lists some of the commonly used medicines with anticholinergic effects in older veterans.

Individual pharmacokinetic and pharmacodynamic variability, the number of medicines, dosages prescribed, drug interactions, and prevalence and severity of co-morbidities may also influence cumulative anticholinergic burden and severity of adverse effects.4, 18

The increase in the number of medicines, including prescribed and self-prescribed over the counter medicines used by many older people, may contribute to an unintended high anticholinergic burden.2, 3, 11 Herbal preparations such as knotweed (polygonum aviculare) as well as over the counter medicines for coughs and colds, antihistamines, travel sickness products and antidiarrhoeals may have anticholinergic properties.4

Ask your patient specific questions about self-prescribed medicines they may be taking.

Be alert to the cholinergic effects of anticholinesterases. Avoid prescribing anticholinergic medicines to compensate for the cholinergic effects of anticholinesterases. If an anticholinergic medicine is prescribed, and you stop the anticholinesterase, the effects of the anticholinergic medicine may be magnified.12

Note: The list of medicines is based on Duran et al.’s 2013 Systematic review of anticholinergic risk scales in older adults (reviewing 7 studies, one of which was Australian), the Australian Medicines Handbook, Martindale: The Complete Drug Reference and expert opinion.

Step 2: Review your patient’s medicines

Identify medicines to consider ceasing or substituting: target medicines of lesser benefit to your patient.19 Assess whether your patient is taking their medicines as prescribed, potential adverse effects, such as risk of falls and cognitive decline, indications, time of benefit and interactions.20 Consider recommending a Medicines Review (HMR or RMMR) by an accredited pharmacist. Ask the pharmacist to specifically consider the anticholinergic burden. Consider consulting the opinion of a geriatrician in difficult cases.

Step 3: If problematic, ask the question: is a medicine essential?

If a medicine is not essential, can it be ceased? Ceasing a medicine with anticholinergic effects may not always be possible. Consider, in consultation with your patient, their goals and expectations, co-morbidities and individual preferences when making a decision.4, 19

Once you have confirmed the medicines to be ceased and a plan has been developed with your patient, begin by ceasing one medicine at a time. Monitor your patient closely and gradually taper the medicine.19 Talk to your patient about possible withdrawal effects, such as anxiety, nausea, vomiting, headache and dizziness. Advise your patient to talk to you if any of these symptoms worry them.21

If not, can the dose, frequency or duration of the medicine be reduced?

When a medicine with anticholinergic effects is essential and the dose, frequency or duration cannot be reduced, advise your patient of non-pharmacological measures to minimise the impact of adverse effects. Examples include artificial tears for dry eyes and increased water intake and a high fibre diet for constipation.5

Potential strategies to reduce the anticholinergic burden4, 12

Urinary incontinence

Consider potential contributing factors, such as disease or pharmacological causes.

Consider lifestyle and physical or behavioural therapies before using medicines.

If prescribing anticholinergics, monitor for adverse effects, especially cognitive function, and cease after 4 weeks if no improvement in urinary symptoms.

Darifenacin and solifenacin may be less likely to cause cognitive impairment or dry mouth than oxybutynin, but may contribute to constipation.

Depression

Treat mild to moderate depression with psychotherapies such as cognitive behavioural therapy, mindfulness and interpersonal therapy, supportive counselling and problem-solving techniques as first line therapies where possible.

If prescribing medicines, consider escitalopram or sertraline: they have less potential for drug interactions.

If prescribing a tricyclic antidepressant (TCA), consider nortriptyline as there is a lower incidence of anticholinergic adverse effects than for other TCAs.22

Behavioural and psychotic disorders including those associated with dementia

PROVIDED BY: University of South Australia - Quality Use of Medicines and Pharmacy Research Centre

IN ASSOCIATION WITH: Discipline of General Practice, The University of Adelaide | School of Public Health, The University of Adelaide | NPS MedicineWise | Australian Medicines Handbook | Drug and Therapeutics Information Service

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